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Magnetic In x Ga 1 - x N nanowires at room temperature using Cu dopant and annealing.

Park YH, Ha R, Park TE, Kim SW, Seo D, Choi HJ - Nanoscale Res Lett (2015)

Bottom Line: The typical diameter of the Cu:In x Ga1 - x N nanowires was 80 to 150 nm, with a typical length of hundreds of micrometers.The as-grown nanowires exhibited diamagnetism.After annealing, the nanowires exhibited ferromagnetism with saturation magnetic moments higher than 0.8 μB (1 μB × 10(-24) Am(2)) per Cu atom at room temperature by the measurements using a superconducting quantum interference device (SQUID) magnetometer.

View Article: PubMed Central - PubMed

Affiliation: Department of Materials Science and Engineering, Yonsei University, Seoul, 120-749, Republic of Korea, younhopark@yonsei.ac.kr.

ABSTRACT
Single-crystal, Cu-doped In x Ga1 - x N nanowires were grown on GaN/Al2O3 substrates via a vapor-liquid-solid (VLS) mechanism using Ni/Au bi-catalysts. The typical diameter of the Cu:In x Ga1 - x N nanowires was 80 to 150 nm, with a typical length of hundreds of micrometers. The as-grown nanowires exhibited diamagnetism. After annealing, the nanowires exhibited ferromagnetism with saturation magnetic moments higher than 0.8 μB (1 μB × 10(-24) Am(2)) per Cu atom at room temperature by the measurements using a superconducting quantum interference device (SQUID) magnetometer. X-ray absorption and X-ray magnetic circular dichroism spectra at Cu L 2,3-edges indicated that the doped Cu had a local magnetic moment and that its electronic configuration was mainly 3d (9). It possessed a small trivalent component, and thus, the n-type behavior of electrical property is measured at room temperature.

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Scanning electron micrograph and results of electrical measurement. (a) Scanning electron micrograph of the electric device. The inset shows the close-up of the nanowire channel and the scale bar is 100 nm. (b) Results of electrical measurement with various VSD at 300 K.
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Fig4: Scanning electron micrograph and results of electrical measurement. (a) Scanning electron micrograph of the electric device. The inset shows the close-up of the nanowire channel and the scale bar is 100 nm. (b) Results of electrical measurement with various VSD at 300 K.

Mentions: The annealing could make the nanowires increase the hole concentration due to dissociating Cu by occupying the interstitial sites and substituted Ga or In vacancies in the InGaN lattice. For investigating the electric properties, we fabricated a field-effect transistor using bottom gate voltage on one Cu-doped InxGa1 - xN nanowire channel after the annealing process, as shown in Figure 4a. In the inset of Figure 4a, the close-up of the triangle nanowire channel and the diameter is about 120 nm, and the channel length is about 1.5 μm. Figure 4 shows the gate voltage dependence of the source-drain current (ISD) at various source-drain voltages (VSD), which indicates n-type behavior. This result is similar to those found in previous papers that reported n-type electrical behavior[11, 18], but these are inconsistent with the evolution of hole-mediated magnetism. The InxGa1 - xN system including nanowires in this study has n-type electrical behavior due to the structural defects. In the system, Cu could act as p-type dopant if it fully substitutes Ga or In sites and ionized. In this study, however, the Cu dopants may not yet fully occupy the Ga or In sites in the In-Ga-N lattice by the annealing process, and thus, the n-type behavior was still observed although the magnetism was evolved by Cu.Figure 4


Magnetic In x Ga 1 - x N nanowires at room temperature using Cu dopant and annealing.

Park YH, Ha R, Park TE, Kim SW, Seo D, Choi HJ - Nanoscale Res Lett (2015)

Scanning electron micrograph and results of electrical measurement. (a) Scanning electron micrograph of the electric device. The inset shows the close-up of the nanowire channel and the scale bar is 100 nm. (b) Results of electrical measurement with various VSD at 300 K.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
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getmorefigures.php?uid=PMC4493842&req=5

Fig4: Scanning electron micrograph and results of electrical measurement. (a) Scanning electron micrograph of the electric device. The inset shows the close-up of the nanowire channel and the scale bar is 100 nm. (b) Results of electrical measurement with various VSD at 300 K.
Mentions: The annealing could make the nanowires increase the hole concentration due to dissociating Cu by occupying the interstitial sites and substituted Ga or In vacancies in the InGaN lattice. For investigating the electric properties, we fabricated a field-effect transistor using bottom gate voltage on one Cu-doped InxGa1 - xN nanowire channel after the annealing process, as shown in Figure 4a. In the inset of Figure 4a, the close-up of the triangle nanowire channel and the diameter is about 120 nm, and the channel length is about 1.5 μm. Figure 4 shows the gate voltage dependence of the source-drain current (ISD) at various source-drain voltages (VSD), which indicates n-type behavior. This result is similar to those found in previous papers that reported n-type electrical behavior[11, 18], but these are inconsistent with the evolution of hole-mediated magnetism. The InxGa1 - xN system including nanowires in this study has n-type electrical behavior due to the structural defects. In the system, Cu could act as p-type dopant if it fully substitutes Ga or In sites and ionized. In this study, however, the Cu dopants may not yet fully occupy the Ga or In sites in the In-Ga-N lattice by the annealing process, and thus, the n-type behavior was still observed although the magnetism was evolved by Cu.Figure 4

Bottom Line: The typical diameter of the Cu:In x Ga1 - x N nanowires was 80 to 150 nm, with a typical length of hundreds of micrometers.The as-grown nanowires exhibited diamagnetism.After annealing, the nanowires exhibited ferromagnetism with saturation magnetic moments higher than 0.8 μB (1 μB × 10(-24) Am(2)) per Cu atom at room temperature by the measurements using a superconducting quantum interference device (SQUID) magnetometer.

View Article: PubMed Central - PubMed

Affiliation: Department of Materials Science and Engineering, Yonsei University, Seoul, 120-749, Republic of Korea, younhopark@yonsei.ac.kr.

ABSTRACT
Single-crystal, Cu-doped In x Ga1 - x N nanowires were grown on GaN/Al2O3 substrates via a vapor-liquid-solid (VLS) mechanism using Ni/Au bi-catalysts. The typical diameter of the Cu:In x Ga1 - x N nanowires was 80 to 150 nm, with a typical length of hundreds of micrometers. The as-grown nanowires exhibited diamagnetism. After annealing, the nanowires exhibited ferromagnetism with saturation magnetic moments higher than 0.8 μB (1 μB × 10(-24) Am(2)) per Cu atom at room temperature by the measurements using a superconducting quantum interference device (SQUID) magnetometer. X-ray absorption and X-ray magnetic circular dichroism spectra at Cu L 2,3-edges indicated that the doped Cu had a local magnetic moment and that its electronic configuration was mainly 3d (9). It possessed a small trivalent component, and thus, the n-type behavior of electrical property is measured at room temperature.

No MeSH data available.


Related in: MedlinePlus